This invention relates to an insulation material suitable for use on subsea equipment in deep water applications.
Offshore oil and gas wells are being developed in deeper waters where ambient seawater temperatures near the seabed are quite cold, typically only a few degrees above the freezing point of water. These very cold conditions can lead to plugging of the subsea wells and connected flowlines if the petroleum products produced from the wells are allowed to cool down to ambient temperature. In most cases, the temperature of the oil and/or gas produced from these wells is relatively hot (150xc2x0 F. to 250xc2x0 F. or more) within the reservoir. The fluids lose heat as they flow through the subsea equipment and pipelines which bring the fluids to a surface based processing facility. If the fluids fall below certain limits (typically in the range of 50xc2x0 F. to 70xc2x0 F.) deposition of paraffin wax and/or formation of methane hydrates can lead to flow restrictions and/or blockage of the subsea production system. Thus, particularly for deep water systems, it is desirable to provide effective thermal insulation on the subsea equipment to prevent excessive cooling of the produced fluids before they reach the processing facility.
Known insulation materials include polymer foams, nearly incompressible polymers, and nearly incompressible polymers filled with very small (e.g., microscopic) solid ceramic beads or hollow plastic or glass beads. Polymer foams provide good insulation in low pressure applications, but collapse under high pressure in deep water. Nearly incompressible polymers maintain their integrity, but are not good insulators.
Nearly incompressible polymers filled with very small (e.g., microscopic) hollow ceramic or hollow glass beads provide good insulation. Unfortunately, these materials are quite hard and brittle, are difficult to install, and are prone to cracking. Cracking occurs when the insulation material and underlying steel equipment are heated and cooled. During heating, the inner surface of the insulation material (adjacent the hot steel equipment) expands more than the outer surface of the insulation material (adjacent the cold sea water). This differential expansion causes cracking. During cooling, the insulation material shrinks more and faster than the steel equipment, causing more cracking.
There is a need or desire for an insulation material which does not collapse under pressure, does not crack, is easy to install, and provides effective insulation at low temperatures.
The present invention is an insulation material suitable for use in deep sea applications, which alleviates the problems of collapsing, cracking, and insufficient performance associated with prior art materials. The insulation material of the invention includes a first (xe2x80x9cglobalxe2x80x9d) polymer matrix made from a flexible elastomeric thermoset or thermoplastic polymer material. Contained within the first polymer matrix are a plurality of macro-beads having mean diameters of about 0.05 to about 1.0 inch. Each of the macro-beads is formed with a second polymer matrix that is generally more rigid and less flexible than the first polymer matrix, and is made from a relatively inelastic thermoset or thermoplastic polymer material. Contained within the second polymer matrix are a plurality of insulative micro-beads having mean diameters of about 0.0003 to about 0.125 inch, and having an interior which may be partially hollow and gas filled, or may be solid.
During use, the more rigid macro-beads provide insulative properties similar to the best prior art deep sea insulative materials, made of the brittle composite described above. The elastic polymer matrix containing the macro-beads provides flexibility to the insulative material by permitting thermal expansion and contraction of the macro-beads, and of the deep sea equipment being insulated. The elastic polymer matrix surrounding the macro-beads simply stretches and retracts in response to the thermal expansion and contraction of the macro-beads and/or the insulated equipment, thus avoiding the cracking associated with the most effective prior art insulative materials.
With the foregoing in mind, it is a feature and advantage of the invention to provide an improved insulative material which protects equipment and pipelines from cold sea water temperatures, and withstands high external pressure, deflection-induced stresses and thermally-induced dimensional stresses.
It is also a feature and advantage of the invention to provide a method of applying the improved insulative material to deep sea equipment and/or pipelines.
These and other features and advantages will become further apparent from the following detailed description of the presently preferred embodiments, read with the accompanying drawing.